Compressor with scroll compression mechanism

ABSTRACT

In a compressor with a scroll compression mechanism having a stationary scroll and a movable scroll, a bearing through which the movable scroll is rotatably connected to a crank portion is disposed in a bearing box. The bearing box is provided for defining a back side room into which high-pressure refrigerant discharged from a discharge hole of an end plate of the movable scroll is introduced. The back side room is partitioned from the compression room by the end plate of the movable scroll to be opposite to the compression room, and a seal member which is disposed to air-tightly partition the back side room and a suction room of the compressor. Thus, a discharge pressure of refrigerant is applied from a back side of the movable scroll only at a position corresponding to the back side room. Accordingly, it is possible to reduce a compression thrust force without using a pressure adjustment valve.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to and claims priority from Japanese Patent Applications No. Hei. 11-365035 filed on Dec. 22, 1999, and No. Hei. 11-365036 filed on Dec. 22, 1999, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a compressor with a scroll compression mechanism, which is suitabley applied to a vapor compression refrigerant cycle.

[0004] 2. Description of Related Art

[0005] In a conventional compressor with a scroll compression mechanism described in JP-A-3-37385, a discharge pressure of compressed refrigerant is adjusted by a pressure adjustment valve such as a pressure-constant valve, and is applied to a back side surface of a movable scroll so that a thrust force applied to the movable scroll in a direction parallel to a shaft is reduced. However, in this compressor, it is necessary to provide the pressure adjustment valve, the structure of the compressor with the scroll compression mechanism can be made complex.

[0006] On the other hand, in a compressor with a scroll compression mechanism described in JP-A-11-2194, a volume of a compression room is reduced while a movable scroll rotates relative to a stationary scroll. A discharge hole is provided at an approximate center position of an end plate of the movable scroll, where the volume of the compression room becomes minimum, and a discharge valve is provided to prevent a fluid from reversely flowing into the compression room from the discharge hole. However, a thickness of the end plate of the movable scroll is generally made thicker for fixing the discharge valve to the end plate of the movable scroll using a bolt. When the thickness of the end plate becomes thicker, the volume of the discharge hole becomes larger, and the dead volume becomes larger. Accordingly, efficiency of the compressor is deteriorated, and the size of the compressor becomes larger.

SUMMARY OF THE INVENTION

[0007] In view of the foregoing problems, it is an object of the present invention to provide a compressor with a scroll compression mechanism, which reduces a thrust force applied to a movable scroll without using a pressure adjustment valve.

[0008] It is an another object of the present invention to provide a compressor with a scroll compression mechanism, in which a check valve can be readily simply fixed without increasing a size of the compressor.

[0009] According to the present invention, in a compressor with a scroll compression mechanism having a stationary scroll and a movable scroll, a volume of a compression room defined by the stationary scroll and the movable scroll is changed to suck and compress the fluid, and the compressed fluid is discharged from a discharge hole provided in an end plate of the movable scroll. The compressor includes a shaft for driving the movable scroll, the shaft has a crank portion at a longitudinal end side, and the crank portion is shifted relative to a rotation axis of the movable scroll. A bearing, through which the movable scroll is rotatably connected to the crank portion, is disposed in a bearing box for receiving therein the bearing and for defining a back side room into which high-pressure fluid discharged from the discharge hole is introduced. Further, the back side room is partitioned from the compression room by the end plate of the movable scroll to be opposite to the compression room, and a seal member is disposed to air-tightly partition the back side room and a fluid suction side of the compression room. Accordingly, a discharge pressure of the fluid is applied from a back surface side of the movable scroll only at a position corresponding to the back side room. Thus, it can prevent a back thrust force due to the pressure of the back side room from being larger than a compression thrust force due to a compression reaction force. As a result, compression thrust force applied to the movable scroll can be set lower without using a pressure adjustment valve.

[0010] Preferably, the bearing box is disposed to protrude from the end plate of the movable scroll to a side opposite to the compression room, and the seal member is disposed between the bearing box and the shaft. Therefore, the high-pressure back side including the back side room can be readily air-tightly partitioned from the fluid suction side of the compression room.

[0011] Preferably, a check valve for opening and closing the discharge hole is disposed to prevent the fluid discharged from the compression room from reversely flowing into the compression room, and the check valve is inserted between the end plate of the movable scroll and the bearing to be fixed to the end plate of the movable scroll. Therefore, it is possible to reduce a thickness of the end plate of the movable scroll, and the check valve can be readily simply fixed without increasing the size of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of a preferred embodiment when taken together with the accompanying drawings, in which:

[0013]FIG. 1 is a diagrammatic view showing a vapor compression refrigerant cycle according to a preferred embodiment of the present invention;

[0014]FIG. 2 is a sectional view showing a compressor with a scroll compression mechanism according to the embodiment; and

[0015]FIG. 3A is an enlarged view showing a discharge hole structure of the compressor, and FIG. 3B is a front view of a discharge valve of the compressor, according to the embodiment.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

[0016] A preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. In this embodiment, the present invention is typically applied to an electrical compressor where a scroll compression mechanism (scroll compressor) is integrated with an electrical motor.

[0017] As shown in FIG. 1, a vapor compression refrigerant cycle for a vehicle air conditioner includes an electrical compressor 100, a condenser 200 as a radiator for cooling refrigerant discharged from the electrical compressor 100, a receiver 300 for separating refrigerant discharged from the radiator 200 into gas refrigerant and liquid refrigerant, a capillary tube 400 for decompressing liquid refrigerant flowing from the receiver 300, and an evaporator 500 for evaporating refrigerant decompressed by the capillary tube 400. In the receiver 300, liquid refrigerant is separated from gas refrigerant, and is stored therein as a surplus refrigerant of the refrigerant cycle.

[0018] Next, a structure of the electrical compressor 100 is described in detail. A scroll compression unit (compression mechanism Cp) is constructed by a stationary scroll 111, a movable scroll (i.e., rotatable scroll) 112 and the like. The stationary scroll 111 is used as a part of a compressor housing 110 for accommodating the compression unit Cp. The compressor housing 110 is made of aluminum, for example.

[0019] A partition wall 114 is disposed in the compressor housing 110 to be fixed to the compressor housing 110 by a bolt and to partition a suction room (i.e., a space where the movable scroll 112 rotates) 113 and a discharge room 121 (motor room) from each other. The stationary scroll 111 has a spiral-shaped teeth portion 111 a provided on an approximate circular end plate 111 b. Similarly, the movable scroll 112 has a spiral-shaped teeth portion 112 a provided on an approximate circular end plate 112 b. When the movable scroll 112 rotates relative to the stationary scroll 111, a volume of an operation room (i.e., compression room) v defined by the stationary scroll 111 and the movable scroll 112 is changed. In the operation room V, refrigerant (fluid) is sucked and is compressed. Refrigerant compressed in the operation room V is discharged from a discharge hole 112 c provided in the end plate 112 b of the movable scroll 112.

[0020] A shaft 115 for rotating the movable scroll 112 has a crank portion 115 a which is shifted from a rotation axis CL of the movable scroll 112, and the movable scroll 112 is rotatably attached to the crank portion 115 a through a bearing 116. The shaft 115 is rotatably supported by radial-rotatable bearings 119 a, 119 b.

[0021] A back compression room 117 (back side room), into which high-pressure refrigerant discharged from the discharge hole 112 c is introduced, is provided at a side of the end plate 112 b opposite to the operation room V. That is, the back compression room 117 and the operation room V are partitioned by the end plate 112 b of the movable scroll 112. Further, an approximate cylindrical bearing box 112 d for accommodating therein the bearing 116 is integrated with the end plate 112 b of the movable scroll 112.

[0022] The bearing 116 is press-fitted into the bearing box 112 d by a stationary fit, and the crank portion 115 a is fitted to the bearing 116 by a running fit. Further, a first refrigerant passage 115 b, through which high-pressure refrigerant discharged in the back compression room 117 is introduced into the discharge room 121, is provided in the crank portion 115 a and the shaft 115. On the other hand, a first seal member 118 a made of resin (e.g., Teflon) is disposed to air-tightly partition the back compression room 117 and the suction room 113 from each other. Further, a second seal member 118 b made of resin (e.g., Teflon) is disposed to air-tightly partition the suction room 113 and the discharge room 121 from each other.

[0023] The first seal member 118 a is disposed between the crank portion 115 a of the shaft 115 and the bearing box 112 d, and slidably contacts the crank portion 115 a for air-tightly partitioning the back compression room 117 and the suction room 113. On the other hand, the second seal member 118 b is disposed between the partition wall 114 and the shaft 115, and slidably contacts the shaft 115 to air-tightly partition the discharge room 121 and the suction room 113.

[0024] A first oil passage 115 c is provided so that lubrication oil mixed in refrigerant flowing through the first refrigerant passage 115 b can be introduced into the bearing 116 and the first seal member 118 a. Further, a second oil passage 115 d is provided so that lubrication oil mixed in the refrigerant flowing through the first refrigerant passage 115 b is introduced into the second seal member 118 b and the bearing 119 a for rotatably supporting the shaft 115. On the other hand, lubrication oil from refrigerant flowing in the discharge room 121 is supplied to the bearing 119 b.

[0025] As shown in FIGS. 3A and 3B, a reed-like discharge valve (reed valve, check valve) 117 a is disposed to open and close the discharge hole 112 c, and to prevent refrigerant discharged from the operation room V from reversely flowing into the operation room V. A stopper 117 b is disposed to regulate a maximum opening degree of the discharge valve 117 a. The discharge valve 117 a and the stopper 117 b are fixed to the end plate 112 b of the movable scroll 112 while being inserted between the end plate 112 b of the movable scroll 112 and the bearing 116. A stopper ring 116 a is disposed in the bearing box 112 d to prevent the bearing 116 from being removed from the bearing box 112 d.

[0026] The discharge room 121 (motor room) is defined by a motor housing 120 made of aluminum, for example. A DC brushless motor Mo for driving the compression unit Cp is accommodated in the discharge room 121, and the discharge room 121 is provided to communicate with a discharge side of the compression unit Cp. The motor Mo includes a stator 122, and a magnetic rotor 123 rotating in the stator 122. The stator 122 is composed of a stator core 122 a fixed in the motor housing 120 by a shrinkage fit, and a winding 122 b wound in the stator core 122 a. The magnet rotor 123 penetrate through the partition wall 114, and is integrally fixed to the shaft 115 for rotating the movable scroll 122 of the compression unit Cp.

[0027] As shown in FIG. 2, a second refrigerant passage 115 e is provided at one end side (i.e., right end side in FIG. 2) of the shaft 115. Through the second refrigerant passage 115 e, high-pressure refrigerant flowing in the discharge room 121 while cooling the motor Mo is introduced into an outside of the a discharge port 130 from the discharge port 130.

[0028] According to the present invention, in the scroll compression unit Cp (scroll compression mechanism), the volume of the operation room V is reduced while the operation room V moves from a swirl outside to a swirl center. Therefore, a thrust force due to a compression reaction force applied to the movable scroll 112 is not equal in an entire area of the end plate 112 b of the movable scroll 112. Accordingly, when a discharge pressure of high-pressure refrigerant is simply applied to the back side surface of the movable scroll 112 without using a pressure adjustment valve, a back thrust force due to the discharge force applied to the back side surface of the movable scroll 112 may become larger than a compression thrust force due to a compression reaction force, and it is impossible to restrict (remove) the thrust force applied to the movable scroll 112.

[0029] However, according to this embodiment, the back compression room 117 through which high-pressure refrigerant discharged from the discharge hole 112 c is introduced is provided in the bearing box 112 d, and the back compression room 117 is air-tightly partitioned from the suction room 113 by the first seal member 118 a. Therefore, the discharge force of the high-pressure refrigerant is applied to the back surface side of the end plate 112 b of the movable scroll 112 only at a position corresponding to the back compression room 117. As shown in FIG. 3A, because an outer diameter dimension Db of the bearing 116 is smaller than an outer diameter dimension Da of the end plate 112 b, it can prevent the back thrust force from being larger than the compression thrust force. Accordingly, in this embodiment, the compression thrust force can be reduced without using a pressure adjustment valve.

[0030] In this embodiment, the bearing 116 is selected based on the compression thrust force in addition to a radial force applied to the bearing 116.

[0031] Further, the discharge valve 117 a is fixed to the end plate 112 b while being inserted between the end plate 112 b of the movable scroll 112 and the bearing 116. Therefore, the end plate 112 b can be made thinner. Thus, the movable scroll 112 can be made smaller, and the size of the electrical compressor 100 can be simply reduced.

[0032] In this embodiment, the discharge hole 112 c is provided in the end plate 112 c at an approximate center position of the back compression room 117 in a radial direction.

[0033] Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.

[0034] For example, in the above-described embodiment, the present invention is typically applied to the electrical compressor where the an electrical motor is integrated with a scroll compressor. However, the present invention can be applied to a compressor where a driving unit such as an electrical motor is separately provided.

[0035] In the above-described embodiment, the discharge valve 117 a may be fixed to the end plate 112 b by a fastening member such as a bolt on the other hand, the first and second seal member 118 a, 118 b may be omitted, and the back thrust force may be applied to the entire back side surface of the end plate 112 b. In this case, it is necessary to provide a seal member for partitioning a discharge room and a suction room.

[0036] Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims. 

What is claimed is:
 1. A compressor for compressing a fluid, comprising: a compression unit including a stationary scroll having an end plate and a teeth portion protruding from the end plate, and a movable scroll having an end plate and a teeth portion protruding from the end plate, the movable scroll being rotatable relative to the stationary scroll, so that a volume of a compression room defined by the stationary scroll and the movable scroll is changed to suck and compress the fluid, and the compressed fluid is discharged from a discharge hole provided in the end plate of the movable scroll; a shaft for driving the movable scroll, the shaft having a crank portion at a longitudinal end side, which is shifted relative to a rotation axis of the movable scroll; a bearing through which the movable scroll is rotatably connected to the crank portion; a bearing box for receiving therein the bearing and for defining a back side room into which high-pressure fluid discharged from the discharge hole is introduced, the back side room being partitioned from the compression room by the end plate of the movable scroll to be opposite to the compression room; and a seal member which is disposed to air-tightly partition the back side room and a fluid suction side of the compression unit.
 2. The compressor according to claim 1 , wherein the discharge hole is provided at an approximate center position of the back side room in a radial direction perpendicular to the rotation axis of the movable scroll.
 3. The compressor according to claim 1 , wherein: the bearing box is disposed to protrude from the end plate of the movable scroll to a side opposite to the compression room; and the seal member is disposed between the bearing box and shaft.
 4. The compressor according to claim 1 , wherein: the end plate of the movable scroll has an outer peripheral dimension in a radial direction perpendicular to the rotation axis of the movable scroll; and the bearing box has an inner peripheral dimension in the radial direction, which is smaller than the outer peripheral dimension of the movable scroll.
 5. The compressor according to claim 1 , further comprising: an electrical motor for supplying a rotation power to the shaft, wherein the electrical motor includes a motor housing, a rotor integrated with the shaft, and a stator fixed to the motor housing.
 6. The compressor according to claim 1 , further comprising: a check valve for opening and closing the discharge hole, wherein the check valve is disposed to prevent the fluid discharged from the compression room from reversely flowing into the compression room.
 7. The compressor according to claim 6 , wherein the check valve is inserted between the end plate of the movable scroll and the bearing to be fixed to the end plate of the movable scroll.
 8. The compressor according to claim 1 , wherein the fluid is refrigerant for a refrigerant cycle.
 9. A compressor for compressing a fluid, comprising: a compression unit including a stationary scroll having an end plate and a teeth portion protruding from the end plate, and a movable scroll having an end plate and a teeth portion protruding from the end plate, the movable scroll being rotatable relative to the stationary scroll, so that a volume of a compression room defined by the stationary scroll and the movable scroll is changed to suck and compress the fluid, and the compressed fluid is discharged from a discharge hole provided in the end plate of the movable scroll; a shaft for driving the movable scroll, the shaft having a crank portion at a longitudinal end side, which is shifted relative to a rotation axis of the movable scroll; a bearing through which the movable scroll is rotatably connected to crank portion; a bearing box for receiving therein the bearing, the bearing box being provide at a side of the end plate of the movable scroll opposite to the compression room; and a check valve for opening and closing the discharge hole, the check valve being disposed to prevent the fluid discharged from the compression room from reversely flowing into the compression room, wherein the check valve is inserted between the end plate of the movable scroll and the bearing to be fixed to the end plate of the movable scroll.
 10. The compressor according to claim 9 , further comprising: an electrical motor for supplying a rotation power to the shaft, wherein the electrical motor includes a motor housing, a rotor integrated with the shaft, and a stator fixed to the motor housing.
 11. The compressor according to claim 9 , wherein the fluid is refrigerant for a refrigerant cycle. 